Film Grain Simulation Technique for Use in Media Playback Devices

1. A method for simulating a film grain block, comprising the steps of: establishing at least one parameter at least in part in accordance with an attribute of an image block; simulating at least one block of film grain from at least one film grain pattern generated in accordance with the at least one parameter; and blending the at least one i block of film grain with the image block, wherein the blending occurs in decode order.

2. The method according to claim 1 wherein the simulating step is preceded by receipt of a supplemental film grain information message accompanying the image block.

3. The method according to claim 1 further including the step of simulating the at least one block of film grain in display order

4. The method according to claim 1 wherein the simulating step further comprises: scaling cut frequencies for chroma components of the image block; computing an average pixel value for the image block; comparing the average pixel value to the block to a corresponding intensity value in a film grain information message accompanying an image block to be blended with the film grain block; retrieving a block of film grain from a database of film grain blocks; and deblocking vertical edges between adjacent blocks.

5. The method according to claim 4 wherein the cut frequencies for the chroma components are scaled to a 4:2:0 format upon receipt of the at least one parameter in a 4:4:4 chroma format.

6. The method according to claim 4 wherein the step of retrieving a block of film grain further comprises the step of randomly retrieving the block of film grain.

7. The method according to claim 4 wherein the retrieving step further comprises the step of retrieving a block of film grain from a database of pre-computed film grain blocks.

8. The method according to claim 4 further comprising the step of establishing the database of film grain blocks by the steps of: specifying a look up table of Gaussian random values; randomly accessing the look up table; performing an integer inverse transform on values randomly accessed from the look-up table; and deblocking horizontal edges of patterns obtained from the integer inverse transform.

9. The method according to claim 1 wherein simulation of film grain does not occur if a film grain message accompanying the image block specifies inhibiting simulation.

10. The method according to claim 9 further comprising the step of inhibiting film grain simulation if the pixel value lies outside all prescribed bands.

11. A method for simulating a film grain block, comprising the steps of: establishing at least one parameter at least in part in accordance with an attribute of an image block; simulating at least one block of film grain from at least one film grain pattern generated in accordance with the at least one parameter; and blending the at least one block of film grain with the image block, wherein the blending occurs in display order.

12. The method according to claim 11 further including the step of simulating the at least one block of film grain in display order.

13. The method according to claim 11 wherein the simulating step further comprises: scaling cut frequencies for chroma components of the image block; computing an average pixel value for the image block; comparing the average pixel value to the block to a corresponding intensity value in a film grain information message accompanying an image block to be blended with the film grain block; retrieving a block of film grain from a database of film grain blocks; and deblocking vertical edges between adjacent blocks.

14. The method according to claim 13 wherein the cut frequencies for the chroma components are scaled to a 4:2:0 format upon receipt of the at least one parameter in a 4:4:4 chroma format.

15. The method according to claim 13 wherein the step of retrieving a block of film grain further comprises the step of randomly retrieving the block of film grain.

16. The method according to claim 13 wherein the retrieving step further comprises the step of retrieving a block of film grain from a database of pre-computed film grain blocks.

17. The method according to claim 13 further comprising the step of establishing the database of film grain blocks by the steps of: specifying a look up table of Gaussian random values; randomly accessing the look up table; performing an integer inverse transform on values randomly accessed from the look-up table; and deblocking horizontal edges of patterns obtained from the integer inverse transform.

18. The method according to claim 11 wherein simulation of film grain does not occur if a film grain message accompanying the image block specifies inhibiting simulation.

19. The method according to claim 11 further comprising the step of inhibiting film grain simulation if the pixel value lies outside all prescribed bands.

20. Apparatus for simulating a film grain block for blending with an image block, comprising: means for establishing at least one parameter at least in part in accordance with an attribute of the image block; means for simulating at least one block of film grain by generating at least one film grain pattern in accordance with the at least one parameter; and means for blending the at least one block of film grain with the image block, wherein the blending occurs in decode order.

21. The apparatus according to claim 20 wherein the means for simulating film grain simulates the at least one block of film grain in decode order.

22. The apparatus according to claim 20 wherein the simulating means further comprise: means for scaling cut frequencies for chroma components of the image block; means for computing an average pixel value for the image block; means for comparing the average pixel value of the block to a corresponding intensity value in a film grain information message accompanying an image block to be blended with the film grain block; a database of film grain blocks; means for retrieving a block of film grain from the database of film grain blocks; and, means deblocking vertical edges between adjunct blocks.

23. The apparatus according to claim 22 wherein scaling means scale the cut frequencies for the chroma components to a 4:2:0 format upon receipt of the at least one parameter in a 4:4:4 chroma format.

24. The apparatus according to claim 22 wherein the means for retrieving a block of film grain randomly retrieves the film grain block.

25. The apparatus according to claim 22 wherein the database contains pre-computed film grain blocks.

26. Apparatus for simulating a film grain block for blending with an image block, comprising: means for establishing at least one parameter at least in part in accordance with an attribute of the image block; means for simulating at least one block of film grain by generating at least one film grain pattern in accordance with the at least one parameter; and means for blending the at least one block of film grain with the image block, wherein the blending occurs in display order.

27. The apparatus according to claim 26 wherein the means for simulating film grain simulates the at least one block of film grain in display order.

28. The apparatus according to claim 26 wherein the simulating means further comprise: means for scaling cut frequencies for chroma components of the image block; means for computing an average pixel value for the image block; means for comparing the average pixel value of the block to a corresponding intensity value in a film grain information message accompanying an image block to be blended with the film grain block; a database of film grain blocks; means for retrieving a block of film grain from the database of film grain blocks; and, means deblocking vertical edges between adjunct blocks.

29. The apparatus according to claim 28 wherein scaling means scale the cut frequencies for the chroma components to a 4:2:0 format upon receipt of the at least one parameter in a 4:4:4 chroma format.

30. The apparatus according to claim 28 wherein the means for retrieving a block of film grain randomly retrieves the film grain block.

31. The apparatus according to claim 28 wherein the database contains pre-computed film grain blocks.